NGC 2173
| NGC 2173 | |
|---|---|
 | |
| Observation data (J2000 epoch) | |
| Constellation | Mensa[1] |
| Right ascension | 05h 57m 58.0s[2] |
| Declination | −72° 58′ 42″[2] |
| Distance | 158.8 ± 3.3 kly (48.7 ± 1.0 kpc)[3] |
| Apparent magnitude (V) | 11.88[4] |
| Apparent dimensions (V) | 2.60″[2] |
| Physical characteristics | |
| Mass | ~105[5] M☉ |
| Metallicity | [Fe/H] = −0.42[4] dex |
| Estimated age | 1.7±0.2 Gyr.[5] |
| Other designations | NGC 2173, SL 807, LW 348, ESO 33SC34[2][6] |
NGC 2173 is a globular cluster of stars in the southern constellation of Mensa.[1] It was discovered on February 8, 1836 by English astronomer John Herschel.[7] The cluster has an apparent visual magnitude of 11.88,[4] and an angular size of 2.60″.[2] It is located at a distance of approximately 159,000 ly (48.7 kpc) from the Sun.[3]
The cluster is located within the Large Magellanic Cloud, to the southeast of the galaxy's center at a separation of around 11,000 ly (3.5 kpc). A 1986 age estimate based on the main sequence turnoff found a value of 1.8±0.7 Gyr.[8] This was later refined to 1.7±0.2 Gyr.[5] Variations in lower mass element abundances suggest that the cluster has at least two distinct stellar populations with different ages.[5]
In 2018, it was announced by Li et al (2018) that the blue straggler stars in the cluster formed two distinct sequences.[9] However, an objection was raised that this finding was an artifact of field contamination: by applying decontamination techniques, one of the sequences could be shown to be unrelated to the cluster.[10] With the availability of higher precision proper motion data, the existence of the bifurcatated sequence was apparently reconfirmed by Wang et al (2025).[11]
References
[edit]- 1 2 Frommert, Hartmut. "Revised NGC Data for NGC 2173". Students for the Exploration and Development of Space. Retrieved 2026-04-26.
- 1 2 3 4 5 Bica, E.; et al. (September 2008). "A general catalogue of extended objects in the Magellanic System". Monthly Notices of the Royal Astronomical Society. 389 (2): 678−690. arXiv:0806.3049. Bibcode:2008MNRAS.389..678B. doi:10.1111/j.1365-2966.2008.13612.x. S2CID 1867090.
- 1 2 Grocholski, Aaron J.; et al. (August 2007). "Distances to Populous Clusters in the Large Magellanic Cloud via the K-band Luminosity of the Red Clump". The Astronomical Journal. 134 (2): 680–693. arXiv:0705.2039. Bibcode:2007AJ....134..680G. doi:10.1086/519735.
- 1 2 3 Grocholski, Aaron J.; et al. (October 2006). "Ca II Triplet Spectroscopy of Large Magellanic Cloud Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters". The Astronomical Journal. 132 (4): 1630–1644. arXiv:astro-ph/0607052. Bibcode:2006AJ....132.1630G. doi:10.1086/507303.
- 1 2 3 4 Kapse, Shalmalee; et al. (March 2022). "Decoding the Bifurcated Red Giant Branch as a Tracer of Multiple Stellar Populations in the Young Large Magellanic Cloud Cluster NGC 2173". The Astrophysical Journal Letters. 927 (1). id. L10. arXiv:2202.08022. Bibcode:2022ApJ...927L..10K. doi:10.3847/2041-8213/ac551a.
- ↑ "NGC 2173". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-04-26.
- ↑ Seligman, Courtney (September 1, 2020). "New General Catalog Objects: NGC 2150 - 2199". Celestial Atlas. Retrieved 2026-04-26.
- ↑ Mould, J. R.; et al. (1986). "The Age of the Large Magellanic Cloud Globular Cluster NGC 2173 - ADS". The Astrophysical Journal. 309: 39. Bibcode:1986ApJ...309...39M. doi:10.1086/164575.
- ↑ Li, Chengyuan; et al. (March 2018). "An Unexpected Detection of Bifurcated Blue Straggler Sequences in the Young Globular Cluster NGC 2173". The Astrophysical Journal. 856 (1). id. 25. arXiv:1802.02307. Bibcode:2018ApJ...856...25L. doi:10.3847/1538-4357/aaad65.
- ↑ Dalessandro, E.; et al. (January 2019). "The double blue-straggler sequence in NGC 2173: an artifact of field contamination". Astronomy & Astrophysics. 621. id. A45. arXiv:1811.01016. Bibcode:2019A&A...621A..45D. doi:10.1051/0004-6361/201834011.
- ↑ Wang, Li; et al. (March 25, 2025). "Unveiling Bifurcated Blue Straggler Sequences in NGC 2173: Insights from Binary Evolution". The Astrophysical Journal. 984 (1): 52. arXiv:2503.19966. Bibcode:2025ApJ...984...52W. doi:10.3847/1538-4357/adc575 – via arXiv.org.